Metal sheets find use in various areas including electric appliances, OA machines, automobiles, and building materials. They are usually coated with paint after working into a desired form.
A new practice has recently developed to use prepainted metal sheets for such applications. Precoated metal sheets obviate the necessity of coating by those who work metal sheets. This in turn obviates the necessity of solvent disposal and hence greatly contributes to environmental protection and cost reduction.
Unfortunately, precoated metal sheets are not necessarily satisfactory in scratch resistance and film hardness because the paint used for them is so designed as to have an adequate degree of softness so that the coating film does not crack at the time of working. This weakness restricts their, application areas and deteriorates their finished products due to scratches made at the time of working.
One way to avoid scratches at the time of working is to stick a protective film (consisting of a plastic film and acrylic-based adhesive applied thereto) to the surface of a metal sheet before working and peel it off after working. However, precoated metal sheets still need improvement in film hardness and scratch resistance.
The present invention was completed in view of the foregoing. It is an object of the present invention to provide a photocurable resin composition suitable for production of precoated metal sheets with hard top coating capable of working into metal parts without scratches.